[Novalug] LVM Snapshots

Peter Larsen plarsen at famlarsen.homelinux.com
Sat Dec 18 15:05:44 EST 2010


Sorry for top posting. My andoids mail client sucks.
Regarding snapshots and boot labels - don't. Use uuids and you're past that problem.

The snapshots inherits all from the master including se-contexts. Labels are NOT unique so be very careful using them.

Now I would be very suspecious of a sytem that tries to boot off a snapshot unless that was on the vm host for your guest os. But I see what you are trying to do. Rembember snapshots are two ways. If you create a snapshot and change the original the snapshot stays as the old was. So simply create a snapshot before you change anything; do your changes and test boot. If it fails revert to your snapshot and things are back to normal (takes a while to do since it rewrites all changed blocks).

James Ewing Cottrell 3rd <JECottrell3 at Comcast.NET> wrote:

>  Is it OK to run off a snapshot? Let me clarify.
>
>I installed some big software package and figured I'd take a snapshot to 
>save the starting configuration. It wanted me to do a reboot, and my 
>grub and fstab does mount points by label: root=LABEL=myrootlabel. Well, 
>I forgot to relabel the snapshot via e2label
>and I believe that somehow the snapshot was the one that was booted 
>onto. I became suspicious later when things disappeared out of my /root 
>directory. Interestingly enough, I didn't find them in the other /root 
>directory either.
>
>I had another case where I did something similar. I wanted to create 
>several variants of the Ubuntu distro: regular, KDS, and LXDE.
>So I installed a text only version, added what I thought was a bunch of 
>cool stuff, and made a snapshot for each of the variants. That time I 
>actually did re2label the snapshots, and even changed the UUIDs, and did 
>the equivalent of a tasksel on each variant.
>
>It worked for awhile, but at some point I couldn't get any of the 
>variants to boot or even the original text only version.
>
>Any thoughts? SELinux was off on all systems.
>
>JIM
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